Blood Feud - S2-E22
[Homer goes to the post office to get a letter he accidentally sent to Mr Burns.]
Homer: [In an obviously fake voice.] Hello, my name is Mr Burns. I believe you have a letter for me.
Post Office Clerk: OK, Mr Burns, what's your first name?
Homer: I don't know.
Answer: I'm not sure if this is the one you're thinking of, but an episode of "Ray Bradbury Theatre," called "A Sound of Thunder," dealt with a similar matter: a group of hunters travel back in time to hunt dinosaurs, only to find things have changed when they get back because someone stepped on a butterfly.
Xofer